The present disclosure relates to axle assemblies. In particular, the axle assemblies can have planetary gear sets and more particularly the axle assembly can have a planetary gear set at the input shaft. Specifically, the axle assembly presently disclosed can have an input planetary gear set driven by an electric motor and/or an internal combustion engine for connection to a differential of an axle assembly. The planetary gear set can be packaged for addition outside the housing of the axle assembly for modifying or adapting existing axle assembly having a differential for use with electric power and hybrid systems.
Typically, vehicle axles assemblies are used to transmit power from the engine to the wheels and in many cases to regulate torque from the drive shaft to the wheels such as by regulating the rotational speed of output shafts relative to the rotational speed of the input shaft. Axle assemblies can come in many configurations depending on their use. There are front axle assemblies, rear axle assemblies and tandem axle assemblies. Tandem axles can include a driven axle and secondary dead axle such as a tag axle or pusher axle.
Modern axle assemblies can include an axle housing. The axle housing can have a head assembly portion that houses a differential gear assembly and at least a portion of the input pinion shaft. The head assembly portion of the axle housing can also at least partially house two semi-axles extending from the differential and extending to the left and right wheels. The head assembly can include at least. The differential gear assembly can utilize a planetary gear set or bevel gear set. Most modern axle assemblies for medium to heavy duty or commercial vehicles are designed for use with internal combustion engines which do not require high gear ratios. Typical gear ratio for such axle assemblies having a differential range from about 2.69:1 to as high as about 7.17:1, with many ratios in between.
There is an increasing trend to add electric motors to vehicles to improve performance and fuel efficiency. These hybrid powered systems require specialized or alternative axle assemblies to accommodate smaller higher speed electric motors which require much higher gear ratios. Alternatively, current lower gear ratio axle assemblies can be used with electric motors as long as the electric motor is fairly large work well with the lower gear ratio, i.e. 7.17:1, axle assemblies. For smaller electric motors, alternative axle assemblies providing higher gear ratios such as from about 20:1 to about 80:1 must be used which requires a significant design change. Adapting current low gear ratio axle assemblies for use in hybrid systems without having to take apart or access components internal to the axle assembly housing would allow more vehicles to accommodate electric motors.
The presently disclosed axle assemblies for use with hybrid electric power system and methods of adapting axle assemblies for use with hybrid electric power utilize axle assemblies designed for use with internal combustion engines to also allow use with hybrid electric vehicles with requiring access inside the axle housing. The present disclosure also provides a planetary gear assembly for connection to the outside of the axle assembly housing to adapt the axle assembly for use with hybrid electric powered vehicles.